healthcheck-k8s

healthcheck-k8s

Check if the specified Kubernetes node is schedulable and return as HTTP status code.

Requirements

• Go
• Kubernetes

Installation

$ docker buildx build .

# Port number (required)
export PORT=8080

# Name of header in which client sends a node name (required)
export HEADER_NAME=X-Node

# Path to the kubeconfig, or else falls back to service account token mounted inside the Pod (optional)
export KUBECONFIG=$HOME/.kube/config

# Timeout in milliseconds (optional; zero means infinity)
export TIMEOUT_MS=30000

# IPv4/IPv6 addresses of trusted proxies in CIDR (optional; comma-separated)
export TRUSTED_PROXIES=10.0.0.0/8,172.16.0.0/12,192.168.0.0/16

Testing

Set up

$ make setup-envtest

Run

$ source <(bin/setup-envtest use latest -p env)
$ go test ./...

Usage

$ ./healthcheck-k8s

Normal: node is schedulable

$ curl --dump-header - -H 'X-Node: minikube' localhost:8080
HTTP/1.1 200 OK
Content-Type: text/plain; charset=utf-8
Date: Wed, 01 Jan 2020 00:00:00 GMT
Content-Length: 26

Node(s) are OK: "minikube"

Cordoned: node is unschedulable

$ kubectl cordon minikube
node/minikube uncordoned

$ curl --dump-header - -H 'X-Node: minikube' localhost:8080
HTTP/1.1 503 Service Unavailable
Content-Type: text/plain; charset=utf-8
Date: Wed, 01 Jan 2020 00:00:00 GMT
Content-Length: 52

Node "minikube" is currently undergoing maintenance.

Spec